초록 ▼

The universal fuel assembly has a plurality of elongated corner posts extending longitudinally between and releasably and rigidly interconnecting top and bottom nozzles so as to form a rigid structural skeleton of the fuel assembly. Additionally, a plurality of transverse grids are supported at axia

The universal fuel assembly has a plurality of elongated corner posts extending longitudinally between and releasably and rigidly interconnecting top and bottom nozzles so as to form a rigid structural skeleton of the fuel assembly. Additionally, a plurality of transverse grids are supported at axially spaced locations along the corner posts and a plurality of fuel rods are supported by the grids. Certain groups of the fuel rods are spaced apart laterally from one another by a greater distance than the rest of the fuel rods so as to define a number of elongated channels extending between the top and bottom nozzles. A cluster assembly having a cluster plate with a plurality of elongated rods is adapted to be removably supported on the top nozzle with its rods extending through the channels. The rods can be a plurality of guide thimbles in the case of one cluster assembly, or a plurality of oversized fuel rods in the case of another cluster assembly. The provision of cluster assemblies allows a unique scheme for loading fuel in the reactor core. Cluster assemblies containing burnt fuel can be loaded into fuel assemblies containing fresh fuel and vice versa. Also, a guide fixture mounting guide rods and a pair of comb devices mounting locking bars are utilized to depress springs within the cells of the grids in order to load fuel rods into the grid cells without scratching their exterior surfaces.

대표청구항 ▼

A fuel assembly, comprising in combination: (a) a rigid fuel assembly skeleton defined by (i) an upper end structure having a plurality of openings defined therein; (ii) a lower end structure; (iii) a purality of elongated nonfuel, nonguide thimble, structural members extending longitudinally betwee

A fuel assembly, comprising in combination: (a) a rigid fuel assembly skeleton defined by (i) an upper end structure having a plurality of openings defined therein; (ii) a lower end structure; (iii) a purality of elongated nonfuel, nonguide thimble, structural members extending longitudinally between and rigidly interconnecting said upper and lower end structures; (b) a plurality of transverse grids being supported on said elongated structural members of said fuel assembly skeleton at axially spaced locations therealong between said upper and lower end structures thereof; (c) a plurality of fuel rods extending through and being supported by said grids between said upper and lower end structures of said fuel assembly skeleton so as to extend in generally side-by-side spaced relation to one another and to said elongated nonfuel, structural members of said fuel assembly skeleton, certain groups of said fuel rods in said plurality thereof being spaced apart laterally from one another by a greater distance than the rest of said fuel rods so as to define a plurality of elongated channels extending through said grids and between said upper and lower end structures of said fuel assembly skeleton, said elongated channels thereby being in the form of open spaces extending laterally between said fuel rods of said certain groups thereof and longitudinally between said upper and lower end structures of said fuel assembly skeleton wherein said open spaces are not defined by any physical structure other than said end structures of said fuel assembly skeleton, said grids and said fuel rods of said certain groups thereof, said plurality of elongated channels being in a pattern which matches that of said plurality of openings in said upper end structure of said fuel assembly skeleton; and (d) a cluster assembly removably supportable on said fuel assembly skeleton and having a plurality of elongated hollow guide thimbles, said guide thimbles of said cluster assembly extending from said upper end structure of said fuel assembly skeleton through said openings therein and through said elongated channels toward said lower end structure of said fuel assembly skeleton when said cluster assembly is removably supported by said upper end structure of said fuel assembly skeleton.